Sunday, December 06, 2009

Bees Release Deadly Odor That Shortens Sibling Lifespans

By Janelle Weaver,, 12/2/2009

Here’s one way to get back at your sibling: Release a deadly odor. Honeybee researchers have discovered the first example of a pheromone that shortens the lifespan of other family members — in this case, older sisters.

“Just one little sniff can change your life,” said biologist Gro Amdam of Arizona State University, co-author of a study published Dec. 1 in The Journal of Experimental Biology. “That’s kind of cool.”

Previous research has shown that the presence of larvae in colonies reduces adult bees’ energy stores and shortens the honeybee lifespan. Scientists had also found that larvae release what is known as a “brood pheromone,” which causes adults to consume more pollen to keep up with larval food demand. But little else was known about this rare chemical concoction found only in bees.

When Amdam and colleagues fed synthetic pheromone-laced syrup to adult bees, they found something surprising: It depleted vital stores of a protein called vitellogenin from bees’ fat tissue and shortened their lives dramatically. The life expectancy of entire colonies dropped below 200 days, making it difficult for honeybees to last through winter.

“Just one whiff of the pheromone has the same effect as if the brood were present. That’s pretty mind-boggling,” said University of Arizona entomologist Diana Wheeler, who was not involved in the study.

The pheromone causes vitellogenin to move from fat tissue into the blood, where it is transported to the head glands and converted into a jelly that older sisters feed to the larvae. In effect, the adult workers give up their energy stores to rear their replacements. “It’s the group behavior that matters in the colony, not the life of single bees,” Amdam said. “In that way, you can sometimes think of bees as a mob.”

“It’s the most striking example of colony-level selection I know of,” Wheeler said…

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